Suggestions, anyone? Fourteen year old cat on five meds.

Hi. I have a 97 year old father in law with a sick cat. The cat suddenly would not get up off of the bed, and after two days of this, my father in law called me for suggestions. I took the cat to his vet and they kept him for about 30 hours until releasing him. I was told they ran every test they could and ruled out pretty much of everything except possible pulmonary hypertension. The cat had a fever and a slight elevated white blood count. All other tests were negative. The cat is now on steroids, antibiotics, gabapentin (pain med?), and hypertension meds as well as an appetite stimulant. This morning, I administered the gabapentin and the steroid and this afternoon, I will administer a round of all of the others including another round of what I gave him this morning. I was thinking it might be a good idea to try MMS but would need advice on dosage and how often. He has not yet eaten anything, even with the dose of appetite stimulant yesterday afternoon. 

I don't know if it was the MMS or the meds that the cat's vet prescribed, or the fact that I used both, but the cat is back to his big, strong self and you would never know anything was previously wrong with him. He was completely limp and unresponsive and after three days, he is good as new. That seems pretty miraculous to me.